{
 "cells": [
  {
   "cell_type": "markdown",
   "id": "45ed72de",
   "metadata": {},
   "source": [
    "---\n",
    "* 记录人（学习人）：曾紫涵\n",
    "* 时间：2021-11-29\n",
    "* week14\n",
    "* 学习线上资源：[python官方文档]()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "b20c9058",
   "metadata": {},
   "source": [
    "# 本周学习目标\n",
    "> 1. 函数的定义\n",
    "> 2. 函数的使用\n",
    "> 3. 函数的参数 "
   ]
  },
  {
   "cell_type": "markdown",
   "id": "6a472717",
   "metadata": {},
   "source": [
    "## 1.函数的定义\n",
    "* 定义一个函数的一般步骤"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "id": "8d5d6637",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0 1 1 2 3 5 8 \n"
     ]
    }
   ],
   "source": [
    "a, b = 0, 1\n",
    "while a < 10:\n",
    "    print(a, end=' ') # 0  1  1 2 ...\n",
    "    a, b = b, a+b # a = 1  a = 1  b = 2  a = 2 b = 3\n",
    "print()\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "id": "eafbdb7a",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0 1 1 2 3 5 8 13 21 34 \n"
     ]
    }
   ],
   "source": [
    "a, b = 0, 1\n",
    "while a < 50:\n",
    "    print(a, end=' ') # 0  1  1 2 ...\n",
    "    a, b = b, a+b # a = 1  a = 1  b = 2  a = 2 b = 3\n",
    "print()\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "id": "d5ea4f86",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0 1 1 2 3 5 8 13 21 34 55 89 \n"
     ]
    }
   ],
   "source": [
    "a, b = 0, 1\n",
    "while a < 100:\n",
    "    print(a, end=' ') # 0  1  1 2 ...\n",
    "    a, b = b, a+b # a = 1  a = 1  b = 2  a = 2 b = 3\n",
    "print()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "id": "94c263a2",
   "metadata": {},
   "outputs": [],
   "source": [
    "  def fib(n):    # write Fibonacci series up to n\n",
    "    \"\"\"Print a Fibonacci series up to n.\"\"\"\n",
    "    a,b = 0,1\n",
    "    while a < n:\n",
    "        print(a, end=' ')\n",
    "        a, b = b, a+b\n",
    "    print()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "id": "e6f2248d",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0 1 1 2 3 5 8 13 21 34 55 89 \n"
     ]
    }
   ],
   "source": [
    "fib(100)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "id": "9b5e27b0",
   "metadata": {},
   "outputs": [],
   "source": [
    "# ..... 我想重复使用某一个功能（避免重复造轮子）\n",
    "# .....使用的人可以不懂代码，只要会调用函数即可 function_name()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "f38e3cfc",
   "metadata": {},
   "source": [
    "> 1. 定义函数的一般方法\n",
    "...\n",
    "def function_name(): # 1. function_name 遵循变量定义的规则  区别数学函数==> f(x) python的函数可以自定义名称 \n",
    "   \"\"\"函数的注释\"\"\" # 2. 函数的注释可以和使用者交流\n",
    "   函数体        # 3. 函数体要和定义函数保持一定的tab缩进  \n",
    "    "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "id": "c893b5b9",
   "metadata": {},
   "outputs": [],
   "source": [
    "def fib(n):    # write Fibonacci series up to n\n",
    "    \"\"\"Print a Fibonacci series up to n.\"\"\"\n",
    "    a,b = 0,1\n",
    "    while a < n:\n",
    "        print(a, end=' ')\n",
    "        a, b = b, a+b\n",
    "    print()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "e523eba1",
   "metadata": {},
   "source": [
    "## 函数的使用"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "id": "354449a4",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0 1 1 2 3 5 8 \n"
     ]
    }
   ],
   "source": [
    "fib(10)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "id": "58111309",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0 1 1 2 3 5 8 13 21 34 \n"
     ]
    }
   ],
   "source": [
    "fib(50)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "id": "1e591796",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "0 1 1 2 3 5 8 13 21 34 55 89 \n"
     ]
    }
   ],
   "source": [
    "fib(100)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "id": "f1906748",
   "metadata": {},
   "outputs": [],
   "source": [
    "# 1. 请大家写一个函数 实现hello world\n",
    "# 2. 请大家写一个函数 实现 hello username"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "id": "046008a1",
   "metadata": {},
   "outputs": [],
   "source": [
    "def hello():\n",
    "    \"\"\"打印hello world\"\"\"\n",
    "    print(\"hello world!\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "id": "360daf1e",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "hello world!\n"
     ]
    }
   ],
   "source": [
    "hello()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "id": "da7561da",
   "metadata": {},
   "outputs": [],
   "source": [
    "def hello_user(username):\n",
    "    \"\"\"打印，你好，xxx同学~\"\"\"\n",
    "    print(\"你好，\"+ username.title()+\"同学~\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "id": "1b754603",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "你好，Jack同学~\n"
     ]
    }
   ],
   "source": [
    "hello_user(\"jack\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "ba20fdfe",
   "metadata": {},
   "outputs": [],
   "source": [
    "* 思考： 函数是否必须有参数\n",
    "* 注意：\n",
    ">> 1. 在第一行定义函数中，不需要任何信息就能完成工作，因此括号是空的（即便如此，括号必不可少）\n",
    ">> 2. 要调用函数，可以依次指定函数名以及括号括起的必要信息。在第五行代码中，因为此函数hello（）括号中不需要任何信息，"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "912c3c2e",
   "metadata": {},
   "source": [
    "## 3.函数的参数\n",
    "> 1. 形式参数:\n",
    ">> 1. 定义函数时，写在 function_name 括号立马的参数\n",
    ">> 2. 在定义函数时，形式参数不占空间\n",
    "> 2. 实际参数：\n",
    ">> 1.调用函数时，写在 function_name 括号立马的参数\n",
    ">> 2. 在使用函数时，形式参数被分配空间，变为实际参数"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 27,
   "id": "7a0e62b7",
   "metadata": {},
   "outputs": [],
   "source": [
    "def describe_pet(animal_type,pet_name):\n",
    "    \"\"\"显示宠物信息\"\"\"\n",
    "    print(\"\\nI have a \" + animal_type + \".\")\n",
    "    print(\"My \" + animal_type + \"'s name is\" + pet_name.title() + \".\")"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "58f32d97",
   "metadata": {},
   "source": [
    "* 当函数具有多个参数时\n",
    "> 1. 位置参数\n",
    ">> 1. 形式参数有先后顺序，函数调用过程中应考虑参数的先后顺序，避免出现顺序错误的笑话\n",
    ">> 2. 调用函数过程中要考虑形式参数的个数\n",
    "> 2. 关键字参数\n",
    ">> 1. 调用函数时，通过赋值的方式传递给定义好的形参变量数据\n",
    ">> 2. 关键字参数不考虑先后顺序，因为是指定变量赋值\n",
    "> 3. 默认参数\n",
    ">> 1. 在形式参数中，提前预先设置一个用户可能使用的参数值\n",
    ">> 2. 用户在使用/调用函数时，可以省略不给默认参数赋值\n",
    ">> 3. 用户给默认参数赋值，将替换默认参数的值"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "id": "7d19cdac",
   "metadata": {},
   "outputs": [],
   "source": [
    "def describe_pet(animal_type,pet_name): # animal_type,pet_name 是形式参数 形参\n",
    "    \"\"\"显示宠物信息\"\"\"\n",
    "    print(\"\\nI have a \" + animal_type + \".\")\n",
    "    print(\"My \" + animal_type + \"'s name is \"+pet_name.title() + \".\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 29,
   "id": "d63fddb4",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "I have a dog.\n",
      "My dog's name is 豆豆.\n"
     ]
    }
   ],
   "source": [
    "# 在使用 describe_pet() 函数时 需要考虑 参数的位置，从而进行参数数据的输入（实参的调用）\n",
    "# 位置参数：\n",
    "describe_pet(\"dog\",\"豆豆\") #　要根据　形式参数的位置先后顺序　先写animal_type，再写pet_name\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 30,
   "id": "59851b1b",
   "metadata": {},
   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "describe_pet() missing 2 required positional arguments: 'animal_type' and 'pet_name'",
     "output_type": "error",
     "traceback": [
      "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[1;31mTypeError\u001b[0m                                 Traceback (most recent call last)",
      "\u001b[1;32m<ipython-input-30-f95e5f55e3d1>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m\u001b[0m\n\u001b[1;32m----> 1\u001b[1;33m \u001b[0mdescribe_pet\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[1;31mTypeError\u001b[0m: describe_pet() missing 2 required positional arguments: 'animal_type' and 'pet_name'"
     ]
    }
   ],
   "source": [
    "describe_pet()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 31,
   "id": "2f6bb87d",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "I have a dog.\n",
      "My dog's name is 豆豆.\n"
     ]
    }
   ],
   "source": [
    "# 关键字参数使用\n",
    "describe_pet(pet_name=\"豆豆\",animal_type=\"dog\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 32,
   "id": "d5985992",
   "metadata": {},
   "outputs": [],
   "source": [
    "# 默认参数\n",
    "def describe_pet(pet_name,animal_type=\"dog\"): # animal_type,pet_name 是形式参数 形参\n",
    "    \"\"\"显示宠物信息\"\"\"\n",
    "    print(\"\\nI have a \" + animal_type + \".\")\n",
    "    print(\"My \" + animal_type + \"'s name is \"+pet_name.title() + \".\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 33,
   "id": "6ef32428",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "I have a dog.\n",
      "My dog's name is 豆豆.\n"
     ]
    }
   ],
   "source": [
    "describe_pet(\"豆豆\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 34,
   "id": "5923370e",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "I have a cat.\n",
      "My cat's name is 豆豆.\n"
     ]
    }
   ],
   "source": [
    "describe_pet(\"豆豆\",\"cat\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 35,
   "id": "a7e7c743",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Help on function describe_pet in module __main__:\n",
      "\n",
      "describe_pet(pet_name, animal_type='dog')\n",
      "    显示宠物信息\n",
      "\n"
     ]
    }
   ],
   "source": [
    "help(describe_pet)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 36,
   "id": "5ec06017",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "hello\n",
      "hello\n"
     ]
    }
   ],
   "source": [
    "print(\"hello\",'\\n',\"hello\",sep='')\n",
    "# print(\"hello\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 37,
   "id": "b5ea551c",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Help on built-in function print in module builtins:\n",
      "\n",
      "print(...)\n",
      "    print(value, ..., sep=' ', end='\\n', file=sys.stdout, flush=False)\n",
      "    \n",
      "    Prints the values to a stream, or to sys.stdout by default.\n",
      "    Optional keyword arguments:\n",
      "    file:  a file-like object (stream); defaults to the current sys.stdout.\n",
      "    sep:   string inserted between values, default a space.\n",
      "    end:   string appended after the last value, default a newline.\n",
      "    flush: whether to forcibly flush the stream.\n",
      "\n"
     ]
    }
   ],
   "source": [
    "help(print)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "167aaf7c",
   "metadata": {},
   "outputs": [],
   "source": [
    "--------\n",
    "参数使用过程中的思考与问题：\n",
    "> 1. 思考：关键字参数 和 位置参数 是否可以一起使用？\n",
    ">> 1. positional arguement follows keyword argument(位置参数均要放在关键字参数前面)\n",
    "--------\n",
    "* 以下为测试代码："
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 43,
   "id": "351dfd5f",
   "metadata": {},
   "outputs": [],
   "source": [
    "# 案例1：\n",
    "def test1(x,y,z):\n",
    "    \"\"\"打印x,y,z的值\"\"\"\n",
    "    print(x)\n",
    "    print(y)\n",
    "    print(z)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 44,
   "id": "0a561789",
   "metadata": {},
   "outputs": [
    {
     "ename": "SyntaxError",
     "evalue": "positional argument follows keyword argument (<ipython-input-44-fd583303ea9b>, line 1)",
     "output_type": "error",
     "traceback": [
      "\u001b[1;36m  File \u001b[1;32m\"<ipython-input-44-fd583303ea9b>\"\u001b[1;36m, line \u001b[1;32m1\u001b[0m\n\u001b[1;33m    test1(x=2,3,z=4)\u001b[0m\n\u001b[1;37m              ^\u001b[0m\n\u001b[1;31mSyntaxError\u001b[0m\u001b[1;31m:\u001b[0m positional argument follows keyword argument\n"
     ]
    }
   ],
   "source": [
    "test1(x=2,3,z=4)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 45,
   "id": "cde78e90",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "2\n",
      "3\n",
      "4\n"
     ]
    }
   ],
   "source": [
    "test1(2,y=3,z=4)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 46,
   "id": "c88975cb",
   "metadata": {},
   "outputs": [
    {
     "ename": "SyntaxError",
     "evalue": "positional argument follows keyword argument (<ipython-input-46-32b91fe9ca8b>, line 1)",
     "output_type": "error",
     "traceback": [
      "\u001b[1;36m  File \u001b[1;32m\"<ipython-input-46-32b91fe9ca8b>\"\u001b[1;36m, line \u001b[1;32m1\u001b[0m\n\u001b[1;33m    test1(2,y=3,4)\u001b[0m\n\u001b[1;37m                ^\u001b[0m\n\u001b[1;31mSyntaxError\u001b[0m\u001b[1;31m:\u001b[0m positional argument follows keyword argument\n"
     ]
    }
   ],
   "source": [
    "test1(2,y=3,4)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 47,
   "id": "390aae54",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "2\n",
      "3\n",
      "4\n"
     ]
    }
   ],
   "source": [
    "test1(2,z=4,y=3)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 48,
   "id": "39d51b4b",
   "metadata": {},
   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "test1() got multiple values for argument 'x'",
     "output_type": "error",
     "traceback": [
      "\u001b[1;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[1;31mTypeError\u001b[0m                                 Traceback (most recent call last)",
      "\u001b[1;32m<ipython-input-48-abf767fdec53>\u001b[0m in \u001b[0;36m<module>\u001b[1;34m\u001b[0m\n\u001b[1;32m----> 1\u001b[1;33m \u001b[0mtest1\u001b[0m\u001b[1;33m(\u001b[0m\u001b[1;36m2\u001b[0m\u001b[1;33m,\u001b[0m\u001b[0mx\u001b[0m\u001b[1;33m=\u001b[0m\u001b[1;36m3\u001b[0m\u001b[1;33m,\u001b[0m\u001b[0my\u001b[0m\u001b[1;33m=\u001b[0m\u001b[1;36m1\u001b[0m\u001b[1;33m)\u001b[0m\u001b[1;33m\u001b[0m\u001b[1;33m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[1;31mTypeError\u001b[0m: test1() got multiple values for argument 'x'"
     ]
    }
   ],
   "source": [
    "test1(2,x=3,y=1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 49,
   "id": "d9328663",
   "metadata": {},
   "outputs": [],
   "source": [
    "# 案例2：\n",
    "def test1(x,z,y=3):\n",
    "    \"\"\"打印x,y,z的值\"\"\"\n",
    "    print(x)\n",
    "    print(y)\n",
    "    print(z)\n"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "9c160bd0",
   "metadata": {},
   "source": [
    "## 4.课本实践练习"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 52,
   "id": "1507e453",
   "metadata": {},
   "outputs": [],
   "source": [
    "def search4vowels(word):\n",
    "    \"\"\"判断输入文本出现的元音字母有哪些\"\"\"\n",
    "    vowels = set(\"aeiou\")\n",
    "    word = set(word)\n",
    "    print(vowels & word)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 53,
   "id": "121ea058",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{'e', 'a'}\n"
     ]
    }
   ],
   "source": [
    "search4vowels(\"bfhdfbhjrea\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 54,
   "id": "61a1cdb6",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "{'e', 'i', 'a'}\n"
     ]
    }
   ],
   "source": [
    "search4vowels(\"bfhdfbhjreai\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "cef87b78",
   "metadata": {},
   "outputs": [],
   "source": []
  }
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